American Journal of ORTHODONTICS Volume 69, Number
ORIGINAL
4, April,
1976
ARTICLES
Management of imppactedcanines Samir E. Bishara, D.D.S., D.Orth., MS., Dennis D. Kommer, Michael H. McNeil, D.M.D., Louis N. Montagano, D.D.S., Larry J. Oesterle, D.D.S., and H. Warren Youngquist, D.D.S.
D.D.S.,
Iowa City, Iowa
A
n impacted or unerupted canine tooth is usually easy to diagnose, but the skill and expertise of the orthodontist, the oral surgeon, and the general practitioner are needed to bring it to its proper position. Since maxillary permanent canines are more frequently impacted than are mandibular ones, the emphasis of this article is on the management of maxillary canines. The same general principles can still be applied to both maxillary and mandibular canines. Normal
eruption
of
maxillary
canines
According to Moyers, 7 “The maxillary cuspid follows a more difficult and tortuous path of eruption than any other tooth. At the age of 3 years it is high in the maxilla, with its crown directed mesially and somewhat lingually.” The canine changes its position in the bone: at first, its crown lies in close proximity to the distal aspect of the root of the lateral incisor. As it erupts farther into the oral cavity it tends to upright itself and finally assumes its position in the arch. Records from the Bolton study taken on 5,000 children in the first 12 years of their lives were used by Br0adbent.l He investigated the developing occlusion in the primary and permanent dentitions. Of particular interest was his discussion of the “ugly duckling” stage. He explained that at 7 years the central incisors usually start to erupt while in the maxilla the lateral incisor crowns are flaring distally. The size of the maxilla at this age is sufficient to permit the canines to Orthodontic Department, College of Dentistry, University of Iowa. This investigation was supported in part by United States Public Health Research Grant DE-00853, National Institute of Dental Research, Bethesda,
Service Md.
371
372
Bishara
et al. Image of moves in as source
lingual same
of
object direction radiation
FILM
LINGUAL
Mesial
Source Y
Source
shifted
of rays
A Fig.
1. Tube-shift
technique
BUCCAL
to
localize
the
buccolingual
LINGUAL
position
of
an
BUCCAL
impacted
tooth.
LINGUAL
FILM
FILM
Source moved down Fig.
2. Buccal-object
rule
to localize
the
buccolingual
I
B position
of an impacted
tooth.
assume their normal position. With the normal development of the maxilla the upper canines erupt away from the root ends of the lateral incisors. Broadbent finally stated, “It is obvious that to correct the ‘ugly duckling’ incisor alignment between 8 and 12 years of age is fraught with hazards that are greater in the underdeveloped face than in one that is normal for its age.” Etiology
of impacted
canines
Moyers7 summarized the etiology for impaction as being due to either: (1) primary causes, e.g., (a) rate of root resorption of deciduous teeth, (b) trauma to the primary tooth bud, (c) disturbance in tooth eruption sequence, (d) avail-
Volume Number
Management
69 4
Fig. 3A. Eruption
or movement
of the
canine
can
be measured
of impacted
canines
on standardized
periar
373
Gcal
films.
Fig. 36. relatively
Clinically, in the fixed position.
ability of sure, (g) secondary endocrine Sequelae
oral
cavity,
movement
is measured
from
the
tip
of
the
cusp
to a
space in the arch, (e) rotation of tooth buds, (f) premature root clocanine eruption into the cleft area in cleft-palate individuals ; or (2) causes, e.g., (a) abnormal muscle pressure, (b) febrile disease, (cl disturbances, and (d) vitamin D deficiency.
of impaction
Shafer, Hine, and Levy9 listed seven possible sequelae which can be rel ated to the unerupted canines : (1) labial impaction, usually vertically impacted; (2)
374
Bishm-a et al.
Fig. 4. Postoperative Fig. 5. posure.
Am.
surgical
pack
(photographed
through
a reflecting
Band with bracket cemented to the impacted canine Traction on the canine is done with a Kl Alastik.
at
J. Orthod.
April
1976
mirror). the
time
of
surgical
ex-
lingual impaction, usually horizontally impacted; (3) root resorption of impinged teeth ; (4) referred pain ; (5) infection from partial impaction resulting in pain and trismus ; (6) dentigerous cyst which can possibly become an ameloblastoma ; and (7) self-resorption-which radiographically resembles caries and begins usually in the crown portion of the impacted tooth. On the other hand, the impacted canine may cause no untoward effects during the lifetime of the individual. Rantas examined 105 patients with clefts of the lip and palate. He found that the crown-root development of the maxillary canines was retarded in about 6.7 per cent of the subjects. Whether this retarded development would also increase the incidence of impacted canines in these individuals was not determined. Diagnosis
cmd
localization
of
impacted
canines
Diagnosis is usually made on the basis of both clinical and roentgenographic examinations.
of impacted
Management
Fig. 6. Dead-soft ment
for
force
Fig. 7. When pigtail
stainless application.
the attachment
steel
impacted canine is contraindicated.
wire,
twisted
is in close
in a pigtail proximity
shape, to the
to
canines
be used
neighboring
as an
teeth,
the
375
attachuse
of
1. Clinical. Any one or a combination of the following signs may be present: (a) delayed eruption of one or more of the permanent canines after 14 years of age; (b) prolonged retention of a primary canine; (c) elevation of the soft tissue of the palatal or labial mucosa (depending on canine location) ; (d) distal migration of the lateral incisors with or without a midline shift. 2. Roentgenographic. Impacted canines may be diagnosed during routine dental examination, which usually includes either a full-mouth survey or a Panorex film. Radiographic localization. Different roentgenographic techniques have been advocated to localize the position of unerupted canines. The most common are as follows. 1. PERIAPICAL FILMS.~ (a) Tube-shift technique or Clark’s rule : Two periapical films are taken of the same area, with the horizontal angulation of the cone changed when the second film is taken. If the object in question moves in the same direction as the tube head it is lingually positioned. If it moves in the opposite direction it is situated closer to the source of radiation and therefore is buccally located (Fig. 1). (b) Buccal-object rule : If the vertical angulation of the cone is changed by approximately 20 degrees in two successive periapical films, the buccal object will move in the direction opposite to the source of radiation (Fig. 2). On the other hand, the lingual object will move in the same direction as the source of radiation. The basic principle of this technique deals with the foreshortening and elongation of the images of the films. In summary, a single periapical film can give information as to the relative
Bishara
376
Fig.
8. Bracket
posite
to
tachment
Fig.
9.
edge
directly
the
canine
on the Threaded
method the
et al.
can or cusp
dental
bonded to
tip
to the
facilitate
impacted
force
canine;
application
the
arch
between
the
wire
is stepped
soldered
hook
J. Orthod. Am-i2 1976
down and
op-
the
at-
canine. pin
be
Am.
used rather
used for
as a
method
impacted than
in the
of
attachment
canines. area
to
an
It is preferable of
the
cingulum
to to
unerupted have avoid
incisor. the
pin
inadvertently
on
The the
same incisal
exposing
pulp.
mesiodistal and superior-inferior positions of the object and the use of two periapical films can add the buccolingual dimension. 2. OCCLUSAL FILMS. These also help to determine the buccolingual position of the impacted canine in conjunction with periapical films, provided that the image of the impacted canine is not superimposed on the other teeth. 3. EXTRAORALFILMS. (a) Frontal and lateral cephalograms can sometimes be of aid in determining the position of impacted canines, especially in relation to other facial structures-particularly the maxillary sinus and the floor of the nose. (b) Panorex films are also used to locate impacted teeth in all three planes of space (much the same as using two periapical films in the tube-shift method or
Volume Number
Management
69 4
of impacted
caxines
377
RESTORATION
Fig.
10.
Wire
as a method
Fig. tors
11. The of force
loop
(0.016
inch
of attachment.
use of the lower to the impacted
round
This
method
wire)
partly is not
arch as a source tooth.
incorporated
in a restoration
and
used
advocated.
of
anchorage
and
to
transmit
vertical
vec-
Clark’s rule)-with the exception that, since the source of radiation comes from behind the patient, the movements are reversed for position ; e.g., a palatal impaction will move left to right roentgenographically when the tube head moves from the patient’s right to his left. A labially impacted or positioned tooth will move roentgenographically in the same direction as the tube head because it is farther from the source of radiation than the reference point.lO The importance of localization of impacted teeth is that it is necessary in order to determine both the surgical approach and the feasibility of managing the condition orthodontically. Accurate determination of the relation of the impacted tooth to the adjacent teeth and/or structures is essential if injury to other dental units or facial spaces is to be avoided.
378
Am.
Kish~ara et al.
J. Orthod. A?wil1976
Fig. 12. Case 1. A girl with a palatally impacted maxillary right canine. Dental findings included a normal mesiodistal molar relation, acceptable overbite and overjet, and little crowding in the lower arch. Skeletal, dental, and soft-tissue relations were within normal cephalometric limits. The impacted canine was surgically uncovered and then covered with a celluloid crown. After 31/2 months the celluloid crown was removed and replaced by a band (with a lingual button). Light elastic force between the canine and an 0.018 by 0.025 edgewise wire brought the canine into the line of the arch. The case was treated in one arch in approximately 14 months.
Surgical
exposure
and
methods
of attachmenlt
to the
impacted
canine
There are two methods of bringing impacted canines into the line of occlusion : (1) surgical exposure, allowing natural eruption to occur, and (2) surgical exposure with the immediate placement of an auxiliary attachment through which orthodontic forces can be applied to move the impacted tooth to its proper position in the line of arch. Xurgical exposure to allow natural eruption to occur. This method has many advantages and is most useful when the canine has a correct axial inclination and does not need to be uprighted during its eruption. The progress of canine eruption should be monitored with frequent roentgenograms, using reference points either on an adjacent erupted tooth or on the arch wire (Figs. 3‘1 and 3B). Clark2 treated 2,000 cases successfully by the above method but he used polycarbonate crowns placed over the impacted tooth. His technique can be summarized as follows : (1) A palatal flap is laid back and overlying bone is removed to expose the crown. It is essential that all bone and soft tissue be removed from around the canine crown. (2) The impacted canine is luxated. (3) A polycarbonate crown is fitted to cover the entire crown of the canine and should be made
Maruxgement
Fig.
12 (Cont’d).
For
legend,
see
opposite
of impacted
page.
canines
379
380
Bishara
et al.
Am.
J. Orthod. Awil 197G
13. Case 2. A girl with a palatally impacted maxillary canine and a congenitally missing maxillary left second premolar. Dental findings included a normal mdsiodistal molar relation on the right and an end-to-end relation on the left. The midline had shifted and the lower left canine was in cross-bite. Crowding in the lower arch was estimated to be about 6 mm. Cephalometrically, there was a tendency toward bimaxillary dental protrusion. An attempt was made to uncover the impacted canine surgically but a decision was
Fig.
made were good treated
to extract it for fear of damaging the neighboring teeth. Two lower first premolars removed and the maxillary right first premolar was used as a canine, resulting in interdigitation on this side. Spaces reopened on the opposite side. The case was in both arches in approximately 18 months.
long enough to extend through the window cut in the palatal tissue. The crown is then cemented with surgical paste or regular cement. (4) Prior to suturing the palatal tissue, a trough is cut through the cortical plate from the impacted canine to the alveolar ridge to ease tooth movement. Usually 6 months to a year must elapse before the impacted tooth has erupted sufficiently to permit removal of the polycarbonate crown and replacement of it with a band. If the tooth fails to erupt it is necessary to remove any cicatricial tissue surrounding its crown. Clark indicated that, after a palatally impacted canine has been brought into the line of arch, lingual drift can be prevented by removing a halfmoon-shaped wedge of tissue from the lingual aspect of the canine down to the bone. Surgical exposure with the placement of an auxiliary. After surgical exposure of the impacted tooth, an auxiliary is attached to its crown, either directly to the enamel or indirectly to a band or crown. Orthodontic forces can be transmitted to this attachment for the purpose of moving the tooth into the line of the arch. Two methods are generally accepted. 1. Lewis6 preferred a two-step approach. First the canine is surgically un-
Volume Number
Management
69 4
Fig. 13 (Cont’d).
For
legend,
see
opposite
of impacted
canines
381
page.
covered and the area packed with surgical dressing to avoid filling in of tissues around the tooth (Fig. 4). When, after 3 to 8 weeks, the wound has healed, the pack is removed and a band or other attachment is placed on the impacted tooth (Fig. 5). 2. The second method is actually a one-step approach: the attachment is placed onto the tooth at the time of surgical uncovering (Fig. 6). Methods of attachment. Different methods of attachment to the impacted canine are used, and a few of them are discussed here. 1. Wire: A dead-soft 0.020 inch brass or stainless steel round wire is passed below the cingulum of the impacted canine, with the ends of the wire twisted in a pigtail form and allowed to extend through the palatal tissue (Fig. 6). This method sometimes demands considerable surgical skill and is at times impossible because the impacted tooth is too close to adjacent teeth (Fig. 7). 2. A variation of the above method is to attach a gold chain (with soldered links) to the wire wrapped around the tooth. A light round wire (0.014 inch) is then soldered to the main arch wire (0.020 inch or preferably edgewise). The end of the auxiliary wire is bent in the form of a hook. To activate the system the
302
B&ma
et al.
Am.
J. Orthod. April 1976
Fig. 14. Case 3. A girl with a palatally impacted maxillary canine. Dental findings included a normal mesiodistal molar relation on the left side and an end-to-end relation on the right, with acceptable overbite, overjet, and minimum crowding in the lower arch. Cephalometrically, the patient was within normal limits. The impacted canine was uncovered surgically and a celluloid crown was inserted which was later replaced by a deadsoft stainless steel wire twisted around the neck of the tooth. Alastiks and multilooped arch wires were used to bring the tooth into the line of occlusion. Treatment did not include removal of teeth and both arches were banded. The treatment time was 22 months.
hook at the end of the auxiliary wire is attached to one of the links of the chain, thus applying tension on the tooth. Another use of the chain is to monitor the movement of the impacted tooth by counting the number of links coming out of the tissues in consecutive visits. 3. Band : Many times a band can be fitted and cemented at the time of surgery (with a bracket, hook, or button welded to it) if all the surfaces of the crown of the impacted canine are uncovered. The corresponding tooth in the same arch can be used as a guide in choosing a suitable band for the unerupted tooth (Fig. 5). 4. Cast gold crown or onlay : After the canine has been uncovered and packed, and the tissues have been allowed to heal, an impression is made of the exposed portion of the canine and a gold onlay with a hook or eyelet is constructed and cemented to it. The impression for the crown could also be taken on the opposite tooth in the same arch if the crown is to be fabricated before surgically exposing the impacted canine. 5. Direct bonded attachment: Adhesives can be used to band an attachment directly to the tooth at the time of surgery or after its partial eruption (Fig. 8). One problem with this method [as well as with any method using a cement or
Management
Fig.
14 (Cont’d).
For
legend,
see
opposite
of
impacted
canines
383
page.
adhesive) is the difficulty in obtaining a dry field for bonding at the time of surgery. 6. Threaded pin: A hole of appropriate size is drilled in the tooth and a pin is threaded or cemented into it (Fig. 9). Care must be taken to avoid placing the pin in the pulp chamber. The primary disadvantage of this method is that the tooth will need a restoration after the pin is removed. 7. Wire loop, made of 0.016 inch round wire, may be embedded into a prepared cavity in the crown of the impacted tooth; the cavity is then filled with amalgam or Adaptic (Fig. 10). Dewe13 cautioned against any permanent destruction of tooth structure. The authors agree with this concept and feel that in most cases such destruction of sound tooth structure is neither needed nor warranted. Johnston,4 in an excellent review of the problem of impacted canines, stated that palatal impactions occur almost 50 times as often as labial impactions and the incidence is three times greater in females than in males. He felt that impactions are rare in those cases in which serial extraction procedures have been initiated. He also advocated surgical exposure of the impacted canine and the application of an Orahesive bandage. In 4 to 6 months the tooth will have erupted suf-
384
Fig.
Bishara
15.
cluded
Case
findings was
arch
elastics
continuous was
within were
arch
a labially
relation normal
cemented;
23
with
II molar
were
band
time
4. A girl
a Class
limits.
a ligature used
wire.
Both
to
impacted
and
The
wire
move arches
maxillary
minimum
the were
was
crowding
right
canine.
in the
lower
impacted
canine
was
attached
to an
eyelet
canine banded,
to
a
position
no teeth
uncovered welded
where were
Dental arch.
surgically on
it was
extracted,
findings
in-
Cephalometric the
engaged and
and
band. the
a
Intrawith
a
treatment
months.
ficiently to permit taking a compound impression on which a cast onlay can be made with small loops as a source of attachment. The onlay is then cemented and traction is applied. Johnston further noticed that labially impacted canines are more difficult to manage because ordinarily there is lack of room in the bony trough for one tooth to pass the other. In very few instances, when there is a normal arch form and the deciduous canine is still present, no treatment may be indicated ; when the deciduous canine has been lost a bridge can be inserted. Orthodontic
management
of
impacted
canines
A. One-arch vs. two-arch treatment. Most orthodontic cases do require banding of both maxillary and mandibular arches in order to achieve the desired biomechanical control necessary for optimal results. The lower arch can often be used to great advantage in helping to position the impacted canine in proper occlusion. This is especially true in horizontal impactions. By utilizing the more vertical type of force vectors the canine may be “guided” down from its impacted position. This is best achieved by building the lower arch wire to a heavy rectangular arch wire (0.018 by 0.025 inch or larger). These wires resist gross distortion when forces are applied to them. Heavier arch wires will also distribute the reactive forces over the whole lower arch and therefore minimize adverse tooth movement (Fig. 11).
Mhagement
Fig.
15 (Cont’d).
For
legend,
see
opposite
of impacted
canines
385
page.
On the other hand, treating one arch only, particularly if light arch wires are used, can lead to both undesirable tooth movements and difficulties in properly coordinating and interdigitating the upper and lower arches together. To prevent some of the undesirable sequelae of one-arch treatment, four considerations should be kept in mind: (1) light forces should be used for canine extrusion; (2) continuous tie or stop of the teeth mesial and distal to the canine area may be indicated ; (3 ) a rectangular arch wire should be present before the extrusion
386
Bishara
et al.
mechanics are started (such an arch wire resists to a greater extent the dcformation caused by the extruding force) ; and (4) the lower arch should be reasonably well aligned and leveled (Fig. 12). B. Cuspid vs. pre??zolar estmctios. The prognosis of successfully exposing and guiding the canine to its proper position is often guarded; therefore, in those cases requiring upper premolar extraction, it is desirable to delay this until the prognosis of the impacted tooth is more certain. The prognosis will depend on the position of the impacted canine in the bone, the relationship of the impacted tooth to the roots of the adjacent teeth, ant1 the skill of the oral surgeon. Xost clinicians agree that permanent canines arc important from both esthetic and functional points of view and therefore should bc preserved whenever possible. In difficult impactions, however, it. might be necessary to surgically remove the canine. B decision has to be made as to whether to move the premolar into the ca.nine position or to fill the canine space with a fixed prosthesis. When the orthodontist is considering replacing the canine by a. first premolar, problems related to tooth-size discrepancies and unilateral mechanics must be carefully assCssCC1 for each case before extraction decisions are made. If the decision is maclc to ~los(~ the canine space orthodontically, the first and second prcmolars can be protracted and the case finished in a Class II molar relation on the affected side(s)-unless lower first premolars arc also extracted arnl the molars can then be finished in a Class I relation (Fig. 13). Such a choice of treatment alternatives is possible only if the first premolars are not extracted until the prognosis of the impacteil canine (s) is determined. Summary
In this article an overview of the problem of impacted canines has been presented ancl some of the clinical considerations related to surgical management and types of attachments have been discussed. In the orthodontic management of impacted canines the clinician has to make certain decisions regarding one-arch vs. two-arch treatment and canine vs. first premolar extraction. The factors which might influence such decisions were also discussed. REFERENCES
1. Broadbent, B. H.: Ontogenic development of occlusion, Angle Orthod. 11: 223-241, 1941. 2. Clark, D.: The management of impacted canines: Free physiologic eruption, J. Am. Dent. Assoc. 82: 836840, 1971. 3. Dewel, R. F. : The upper cuspid: .lts development and impaction, Angle Orthod. 19: 79-90, 1949. 4. Johnston, WN. D.: Treatment of palatally impacted canine teeth, A&f. J. ORTHOU. 56: 58% 596,
1969.
5. Landland, 0. E., and Sippy, F.: Manual of dental radiology, Ames, 1969, Tinivesrity of Towa Publications. 6. Lewis, P. D.: Preorthodontie surgery in the treatment of impacted canines, AM. J. ORTHOD. 60: 383-397, 1971. 7. Noyers, R. E.: Handbook of orthodontics, ed. 2, Chicago, 1963, Year Book Medical Publishers, Inc., pp. 83-88. 8. Ranta, R.: On the development of central incisors and canines situated adjacent to the cleft in unilateral total cleft cases. An orthopantomographic and clinical study, Suomen Hammaslaakariseuran Tomituksia 67: 345-349, 1971.
Volume Nz&mber
Management
69 4
of impacted
9. Shafer, W. G., Hine, M. K., and Levy, B. M.: A textbook Philadelphia, 1963, W. B. Saunders Company, pp. 2-75. 10. Turk, M. H., and Katzenell, J.: Panoramic localization, Oral Dental
Science
THE JOURNAL April,
Bldg.
canines
of
oral
pathology,
Surg.
29:
212-215,
307 ed.
2,
1970.
(56648)
60 YEARS
AGO
1916
To extract an irregular tooth would answer but little purpose, if no alteration could be made in the situation of the rest; but we find that the very principle upon which teeth are made to grow irregularly is capable, if properly directed, of bringing them even again. This principle is the power which many parts (especially bones) have of moving out of the way of mechanical pressure. The best time for moving the teeth is in youth, while the jaws have an adapting disposition; for, after a certain time, they do not readily suit themselves to the irregularity of the teeth. This we see plainly to be the case when we compare the loss of a tooth at the age of fifteen years, and at that of thirty or forty. In the first case we find, that the two neighboring teeth approach one another, in every part alike, till they close; but in the second, the distance in the Jaw, between the two neighboring teeth, remains the same, while the bodies will in a small degree incline to one another from want of lateral support. And this circumstance of the bodies of the teeth yielding to pressure upon their base, shows that, even in the adult, they might be brought nearer to one another by art properly applied. (Hunter, John: Natural History of the Teeth, ed. 1, London, 1771, J. Johnson. In Weinberger, Bernard. W.: History of Orthodontia. Internat. J. Orthod. 2: 205, 1916.)
ORIGINAL
4, April,
1976
ARTICLES
Management of imppactedcanines Samir E. Bishara, D.D.S., D.Orth., MS., Dennis D. Kommer, Michael H. McNeil, D.M.D., Louis N. Montagano, D.D.S., Larry J. Oesterle, D.D.S., and H. Warren Youngquist, D.D.S.
D.D.S.,
Iowa City, Iowa
A
n impacted or unerupted canine tooth is usually easy to diagnose, but the skill and expertise of the orthodontist, the oral surgeon, and the general practitioner are needed to bring it to its proper position. Since maxillary permanent canines are more frequently impacted than are mandibular ones, the emphasis of this article is on the management of maxillary canines. The same general principles can still be applied to both maxillary and mandibular canines. Normal
eruption
of
maxillary
canines
According to Moyers, 7 “The maxillary cuspid follows a more difficult and tortuous path of eruption than any other tooth. At the age of 3 years it is high in the maxilla, with its crown directed mesially and somewhat lingually.” The canine changes its position in the bone: at first, its crown lies in close proximity to the distal aspect of the root of the lateral incisor. As it erupts farther into the oral cavity it tends to upright itself and finally assumes its position in the arch. Records from the Bolton study taken on 5,000 children in the first 12 years of their lives were used by Br0adbent.l He investigated the developing occlusion in the primary and permanent dentitions. Of particular interest was his discussion of the “ugly duckling” stage. He explained that at 7 years the central incisors usually start to erupt while in the maxilla the lateral incisor crowns are flaring distally. The size of the maxilla at this age is sufficient to permit the canines to Orthodontic Department, College of Dentistry, University of Iowa. This investigation was supported in part by United States Public Health Research Grant DE-00853, National Institute of Dental Research, Bethesda,
Service Md.
371
372
Bishara
et al. Image of moves in as source
lingual same
of
object direction radiation
FILM
LINGUAL
Mesial
Source Y
Source
shifted
of rays
A Fig.
1. Tube-shift
technique
BUCCAL
to
localize
the
buccolingual
LINGUAL
position
of
an
BUCCAL
impacted
tooth.
LINGUAL
FILM
FILM
Source moved down Fig.
2. Buccal-object
rule
to localize
the
buccolingual
I
B position
of an impacted
tooth.
assume their normal position. With the normal development of the maxilla the upper canines erupt away from the root ends of the lateral incisors. Broadbent finally stated, “It is obvious that to correct the ‘ugly duckling’ incisor alignment between 8 and 12 years of age is fraught with hazards that are greater in the underdeveloped face than in one that is normal for its age.” Etiology
of impacted
canines
Moyers7 summarized the etiology for impaction as being due to either: (1) primary causes, e.g., (a) rate of root resorption of deciduous teeth, (b) trauma to the primary tooth bud, (c) disturbance in tooth eruption sequence, (d) avail-
Volume Number
Management
69 4
Fig. 3A. Eruption
or movement
of the
canine
can
be measured
of impacted
canines
on standardized
periar
373
Gcal
films.
Fig. 36. relatively
Clinically, in the fixed position.
ability of sure, (g) secondary endocrine Sequelae
oral
cavity,
movement
is measured
from
the
tip
of
the
cusp
to a
space in the arch, (e) rotation of tooth buds, (f) premature root clocanine eruption into the cleft area in cleft-palate individuals ; or (2) causes, e.g., (a) abnormal muscle pressure, (b) febrile disease, (cl disturbances, and (d) vitamin D deficiency.
of impaction
Shafer, Hine, and Levy9 listed seven possible sequelae which can be rel ated to the unerupted canines : (1) labial impaction, usually vertically impacted; (2)
374
Bishm-a et al.
Fig. 4. Postoperative Fig. 5. posure.
Am.
surgical
pack
(photographed
through
a reflecting
Band with bracket cemented to the impacted canine Traction on the canine is done with a Kl Alastik.
at
J. Orthod.
April
1976
mirror). the
time
of
surgical
ex-
lingual impaction, usually horizontally impacted; (3) root resorption of impinged teeth ; (4) referred pain ; (5) infection from partial impaction resulting in pain and trismus ; (6) dentigerous cyst which can possibly become an ameloblastoma ; and (7) self-resorption-which radiographically resembles caries and begins usually in the crown portion of the impacted tooth. On the other hand, the impacted canine may cause no untoward effects during the lifetime of the individual. Rantas examined 105 patients with clefts of the lip and palate. He found that the crown-root development of the maxillary canines was retarded in about 6.7 per cent of the subjects. Whether this retarded development would also increase the incidence of impacted canines in these individuals was not determined. Diagnosis
cmd
localization
of
impacted
canines
Diagnosis is usually made on the basis of both clinical and roentgenographic examinations.
of impacted
Management
Fig. 6. Dead-soft ment
for
force
Fig. 7. When pigtail
stainless application.
the attachment
steel
impacted canine is contraindicated.
wire,
twisted
is in close
in a pigtail proximity
shape, to the
to
canines
be used
neighboring
as an
teeth,
the
375
attachuse
of
1. Clinical. Any one or a combination of the following signs may be present: (a) delayed eruption of one or more of the permanent canines after 14 years of age; (b) prolonged retention of a primary canine; (c) elevation of the soft tissue of the palatal or labial mucosa (depending on canine location) ; (d) distal migration of the lateral incisors with or without a midline shift. 2. Roentgenographic. Impacted canines may be diagnosed during routine dental examination, which usually includes either a full-mouth survey or a Panorex film. Radiographic localization. Different roentgenographic techniques have been advocated to localize the position of unerupted canines. The most common are as follows. 1. PERIAPICAL FILMS.~ (a) Tube-shift technique or Clark’s rule : Two periapical films are taken of the same area, with the horizontal angulation of the cone changed when the second film is taken. If the object in question moves in the same direction as the tube head it is lingually positioned. If it moves in the opposite direction it is situated closer to the source of radiation and therefore is buccally located (Fig. 1). (b) Buccal-object rule : If the vertical angulation of the cone is changed by approximately 20 degrees in two successive periapical films, the buccal object will move in the direction opposite to the source of radiation (Fig. 2). On the other hand, the lingual object will move in the same direction as the source of radiation. The basic principle of this technique deals with the foreshortening and elongation of the images of the films. In summary, a single periapical film can give information as to the relative
Bishara
376
Fig.
8. Bracket
posite
to
tachment
Fig.
9.
edge
directly
the
canine
on the Threaded
method the
et al.
can or cusp
dental
bonded to
tip
to the
facilitate
impacted
force
canine;
application
the
arch
between
the
wire
is stepped
soldered
hook
J. Orthod. Am-i2 1976
down and
op-
the
at-
canine. pin
be
Am.
used rather
used for
as a
method
impacted than
in the
of
attachment
canines. area
to
an
It is preferable of
the
cingulum
to to
unerupted have avoid
incisor. the
pin
inadvertently
on
The the
same incisal
exposing
pulp.
mesiodistal and superior-inferior positions of the object and the use of two periapical films can add the buccolingual dimension. 2. OCCLUSAL FILMS. These also help to determine the buccolingual position of the impacted canine in conjunction with periapical films, provided that the image of the impacted canine is not superimposed on the other teeth. 3. EXTRAORALFILMS. (a) Frontal and lateral cephalograms can sometimes be of aid in determining the position of impacted canines, especially in relation to other facial structures-particularly the maxillary sinus and the floor of the nose. (b) Panorex films are also used to locate impacted teeth in all three planes of space (much the same as using two periapical films in the tube-shift method or
Volume Number
Management
69 4
of impacted
caxines
377
RESTORATION
Fig.
10.
Wire
as a method
Fig. tors
11. The of force
loop
(0.016
inch
of attachment.
use of the lower to the impacted
round
This
method
wire)
partly is not
arch as a source tooth.
incorporated
in a restoration
and
used
advocated.
of
anchorage
and
to
transmit
vertical
vec-
Clark’s rule)-with the exception that, since the source of radiation comes from behind the patient, the movements are reversed for position ; e.g., a palatal impaction will move left to right roentgenographically when the tube head moves from the patient’s right to his left. A labially impacted or positioned tooth will move roentgenographically in the same direction as the tube head because it is farther from the source of radiation than the reference point.lO The importance of localization of impacted teeth is that it is necessary in order to determine both the surgical approach and the feasibility of managing the condition orthodontically. Accurate determination of the relation of the impacted tooth to the adjacent teeth and/or structures is essential if injury to other dental units or facial spaces is to be avoided.
378
Am.
Kish~ara et al.
J. Orthod. A?wil1976
Fig. 12. Case 1. A girl with a palatally impacted maxillary right canine. Dental findings included a normal mesiodistal molar relation, acceptable overbite and overjet, and little crowding in the lower arch. Skeletal, dental, and soft-tissue relations were within normal cephalometric limits. The impacted canine was surgically uncovered and then covered with a celluloid crown. After 31/2 months the celluloid crown was removed and replaced by a band (with a lingual button). Light elastic force between the canine and an 0.018 by 0.025 edgewise wire brought the canine into the line of the arch. The case was treated in one arch in approximately 14 months.
Surgical
exposure
and
methods
of attachmenlt
to the
impacted
canine
There are two methods of bringing impacted canines into the line of occlusion : (1) surgical exposure, allowing natural eruption to occur, and (2) surgical exposure with the immediate placement of an auxiliary attachment through which orthodontic forces can be applied to move the impacted tooth to its proper position in the line of arch. Xurgical exposure to allow natural eruption to occur. This method has many advantages and is most useful when the canine has a correct axial inclination and does not need to be uprighted during its eruption. The progress of canine eruption should be monitored with frequent roentgenograms, using reference points either on an adjacent erupted tooth or on the arch wire (Figs. 3‘1 and 3B). Clark2 treated 2,000 cases successfully by the above method but he used polycarbonate crowns placed over the impacted tooth. His technique can be summarized as follows : (1) A palatal flap is laid back and overlying bone is removed to expose the crown. It is essential that all bone and soft tissue be removed from around the canine crown. (2) The impacted canine is luxated. (3) A polycarbonate crown is fitted to cover the entire crown of the canine and should be made
Maruxgement
Fig.
12 (Cont’d).
For
legend,
see
opposite
of impacted
page.
canines
379
380
Bishara
et al.
Am.
J. Orthod. Awil 197G
13. Case 2. A girl with a palatally impacted maxillary canine and a congenitally missing maxillary left second premolar. Dental findings included a normal mdsiodistal molar relation on the right and an end-to-end relation on the left. The midline had shifted and the lower left canine was in cross-bite. Crowding in the lower arch was estimated to be about 6 mm. Cephalometrically, there was a tendency toward bimaxillary dental protrusion. An attempt was made to uncover the impacted canine surgically but a decision was
Fig.
made were good treated
to extract it for fear of damaging the neighboring teeth. Two lower first premolars removed and the maxillary right first premolar was used as a canine, resulting in interdigitation on this side. Spaces reopened on the opposite side. The case was in both arches in approximately 18 months.
long enough to extend through the window cut in the palatal tissue. The crown is then cemented with surgical paste or regular cement. (4) Prior to suturing the palatal tissue, a trough is cut through the cortical plate from the impacted canine to the alveolar ridge to ease tooth movement. Usually 6 months to a year must elapse before the impacted tooth has erupted sufficiently to permit removal of the polycarbonate crown and replacement of it with a band. If the tooth fails to erupt it is necessary to remove any cicatricial tissue surrounding its crown. Clark indicated that, after a palatally impacted canine has been brought into the line of arch, lingual drift can be prevented by removing a halfmoon-shaped wedge of tissue from the lingual aspect of the canine down to the bone. Surgical exposure with the placement of an auxiliary. After surgical exposure of the impacted tooth, an auxiliary is attached to its crown, either directly to the enamel or indirectly to a band or crown. Orthodontic forces can be transmitted to this attachment for the purpose of moving the tooth into the line of the arch. Two methods are generally accepted. 1. Lewis6 preferred a two-step approach. First the canine is surgically un-
Volume Number
Management
69 4
Fig. 13 (Cont’d).
For
legend,
see
opposite
of impacted
canines
381
page.
covered and the area packed with surgical dressing to avoid filling in of tissues around the tooth (Fig. 4). When, after 3 to 8 weeks, the wound has healed, the pack is removed and a band or other attachment is placed on the impacted tooth (Fig. 5). 2. The second method is actually a one-step approach: the attachment is placed onto the tooth at the time of surgical uncovering (Fig. 6). Methods of attachment. Different methods of attachment to the impacted canine are used, and a few of them are discussed here. 1. Wire: A dead-soft 0.020 inch brass or stainless steel round wire is passed below the cingulum of the impacted canine, with the ends of the wire twisted in a pigtail form and allowed to extend through the palatal tissue (Fig. 6). This method sometimes demands considerable surgical skill and is at times impossible because the impacted tooth is too close to adjacent teeth (Fig. 7). 2. A variation of the above method is to attach a gold chain (with soldered links) to the wire wrapped around the tooth. A light round wire (0.014 inch) is then soldered to the main arch wire (0.020 inch or preferably edgewise). The end of the auxiliary wire is bent in the form of a hook. To activate the system the
302
B&ma
et al.
Am.
J. Orthod. April 1976
Fig. 14. Case 3. A girl with a palatally impacted maxillary canine. Dental findings included a normal mesiodistal molar relation on the left side and an end-to-end relation on the right, with acceptable overbite, overjet, and minimum crowding in the lower arch. Cephalometrically, the patient was within normal limits. The impacted canine was uncovered surgically and a celluloid crown was inserted which was later replaced by a deadsoft stainless steel wire twisted around the neck of the tooth. Alastiks and multilooped arch wires were used to bring the tooth into the line of occlusion. Treatment did not include removal of teeth and both arches were banded. The treatment time was 22 months.
hook at the end of the auxiliary wire is attached to one of the links of the chain, thus applying tension on the tooth. Another use of the chain is to monitor the movement of the impacted tooth by counting the number of links coming out of the tissues in consecutive visits. 3. Band : Many times a band can be fitted and cemented at the time of surgery (with a bracket, hook, or button welded to it) if all the surfaces of the crown of the impacted canine are uncovered. The corresponding tooth in the same arch can be used as a guide in choosing a suitable band for the unerupted tooth (Fig. 5). 4. Cast gold crown or onlay : After the canine has been uncovered and packed, and the tissues have been allowed to heal, an impression is made of the exposed portion of the canine and a gold onlay with a hook or eyelet is constructed and cemented to it. The impression for the crown could also be taken on the opposite tooth in the same arch if the crown is to be fabricated before surgically exposing the impacted canine. 5. Direct bonded attachment: Adhesives can be used to band an attachment directly to the tooth at the time of surgery or after its partial eruption (Fig. 8). One problem with this method [as well as with any method using a cement or
Management
Fig.
14 (Cont’d).
For
legend,
see
opposite
of
impacted
canines
383
page.
adhesive) is the difficulty in obtaining a dry field for bonding at the time of surgery. 6. Threaded pin: A hole of appropriate size is drilled in the tooth and a pin is threaded or cemented into it (Fig. 9). Care must be taken to avoid placing the pin in the pulp chamber. The primary disadvantage of this method is that the tooth will need a restoration after the pin is removed. 7. Wire loop, made of 0.016 inch round wire, may be embedded into a prepared cavity in the crown of the impacted tooth; the cavity is then filled with amalgam or Adaptic (Fig. 10). Dewe13 cautioned against any permanent destruction of tooth structure. The authors agree with this concept and feel that in most cases such destruction of sound tooth structure is neither needed nor warranted. Johnston,4 in an excellent review of the problem of impacted canines, stated that palatal impactions occur almost 50 times as often as labial impactions and the incidence is three times greater in females than in males. He felt that impactions are rare in those cases in which serial extraction procedures have been initiated. He also advocated surgical exposure of the impacted canine and the application of an Orahesive bandage. In 4 to 6 months the tooth will have erupted suf-
384
Fig.
Bishara
15.
cluded
Case
findings was
arch
elastics
continuous was
within were
arch
a labially
relation normal
cemented;
23
with
II molar
were
band
time
4. A girl
a Class
limits.
a ligature used
wire.
Both
to
impacted
and
The
wire
move arches
maxillary
minimum
the were
was
crowding
right
canine.
in the
lower
impacted
canine
was
attached
to an
eyelet
canine banded,
to
a
position
no teeth
uncovered welded
where were
Dental arch.
surgically on
it was
extracted,
findings
in-
Cephalometric the
engaged and
and
band. the
a
Intrawith
a
treatment
months.
ficiently to permit taking a compound impression on which a cast onlay can be made with small loops as a source of attachment. The onlay is then cemented and traction is applied. Johnston further noticed that labially impacted canines are more difficult to manage because ordinarily there is lack of room in the bony trough for one tooth to pass the other. In very few instances, when there is a normal arch form and the deciduous canine is still present, no treatment may be indicated ; when the deciduous canine has been lost a bridge can be inserted. Orthodontic
management
of
impacted
canines
A. One-arch vs. two-arch treatment. Most orthodontic cases do require banding of both maxillary and mandibular arches in order to achieve the desired biomechanical control necessary for optimal results. The lower arch can often be used to great advantage in helping to position the impacted canine in proper occlusion. This is especially true in horizontal impactions. By utilizing the more vertical type of force vectors the canine may be “guided” down from its impacted position. This is best achieved by building the lower arch wire to a heavy rectangular arch wire (0.018 by 0.025 inch or larger). These wires resist gross distortion when forces are applied to them. Heavier arch wires will also distribute the reactive forces over the whole lower arch and therefore minimize adverse tooth movement (Fig. 11).
Mhagement
Fig.
15 (Cont’d).
For
legend,
see
opposite
of impacted
canines
385
page.
On the other hand, treating one arch only, particularly if light arch wires are used, can lead to both undesirable tooth movements and difficulties in properly coordinating and interdigitating the upper and lower arches together. To prevent some of the undesirable sequelae of one-arch treatment, four considerations should be kept in mind: (1) light forces should be used for canine extrusion; (2) continuous tie or stop of the teeth mesial and distal to the canine area may be indicated ; (3 ) a rectangular arch wire should be present before the extrusion
386
Bishara
et al.
mechanics are started (such an arch wire resists to a greater extent the dcformation caused by the extruding force) ; and (4) the lower arch should be reasonably well aligned and leveled (Fig. 12). B. Cuspid vs. pre??zolar estmctios. The prognosis of successfully exposing and guiding the canine to its proper position is often guarded; therefore, in those cases requiring upper premolar extraction, it is desirable to delay this until the prognosis of the impacted tooth is more certain. The prognosis will depend on the position of the impacted canine in the bone, the relationship of the impacted tooth to the roots of the adjacent teeth, ant1 the skill of the oral surgeon. Xost clinicians agree that permanent canines arc important from both esthetic and functional points of view and therefore should bc preserved whenever possible. In difficult impactions, however, it. might be necessary to surgically remove the canine. B decision has to be made as to whether to move the premolar into the ca.nine position or to fill the canine space with a fixed prosthesis. When the orthodontist is considering replacing the canine by a. first premolar, problems related to tooth-size discrepancies and unilateral mechanics must be carefully assCssCC1 for each case before extraction decisions are made. If the decision is maclc to ~los(~ the canine space orthodontically, the first and second prcmolars can be protracted and the case finished in a Class II molar relation on the affected side(s)-unless lower first premolars arc also extracted arnl the molars can then be finished in a Class I relation (Fig. 13). Such a choice of treatment alternatives is possible only if the first premolars are not extracted until the prognosis of the impacteil canine (s) is determined. Summary
In this article an overview of the problem of impacted canines has been presented ancl some of the clinical considerations related to surgical management and types of attachments have been discussed. In the orthodontic management of impacted canines the clinician has to make certain decisions regarding one-arch vs. two-arch treatment and canine vs. first premolar extraction. The factors which might influence such decisions were also discussed. REFERENCES
1. Broadbent, B. H.: Ontogenic development of occlusion, Angle Orthod. 11: 223-241, 1941. 2. Clark, D.: The management of impacted canines: Free physiologic eruption, J. Am. Dent. Assoc. 82: 836840, 1971. 3. Dewel, R. F. : The upper cuspid: .lts development and impaction, Angle Orthod. 19: 79-90, 1949. 4. Johnston, WN. D.: Treatment of palatally impacted canine teeth, A&f. J. ORTHOU. 56: 58% 596,
1969.
5. Landland, 0. E., and Sippy, F.: Manual of dental radiology, Ames, 1969, Tinivesrity of Towa Publications. 6. Lewis, P. D.: Preorthodontie surgery in the treatment of impacted canines, AM. J. ORTHOD. 60: 383-397, 1971. 7. Noyers, R. E.: Handbook of orthodontics, ed. 2, Chicago, 1963, Year Book Medical Publishers, Inc., pp. 83-88. 8. Ranta, R.: On the development of central incisors and canines situated adjacent to the cleft in unilateral total cleft cases. An orthopantomographic and clinical study, Suomen Hammaslaakariseuran Tomituksia 67: 345-349, 1971.
Volume Nz&mber
Management
69 4
of impacted
9. Shafer, W. G., Hine, M. K., and Levy, B. M.: A textbook Philadelphia, 1963, W. B. Saunders Company, pp. 2-75. 10. Turk, M. H., and Katzenell, J.: Panoramic localization, Oral Dental
Science
THE JOURNAL April,
Bldg.
canines
of
oral
pathology,
Surg.
29:
212-215,
307 ed.
2,
1970.
(56648)
60 YEARS
AGO
1916
To extract an irregular tooth would answer but little purpose, if no alteration could be made in the situation of the rest; but we find that the very principle upon which teeth are made to grow irregularly is capable, if properly directed, of bringing them even again. This principle is the power which many parts (especially bones) have of moving out of the way of mechanical pressure. The best time for moving the teeth is in youth, while the jaws have an adapting disposition; for, after a certain time, they do not readily suit themselves to the irregularity of the teeth. This we see plainly to be the case when we compare the loss of a tooth at the age of fifteen years, and at that of thirty or forty. In the first case we find, that the two neighboring teeth approach one another, in every part alike, till they close; but in the second, the distance in the Jaw, between the two neighboring teeth, remains the same, while the bodies will in a small degree incline to one another from want of lateral support. And this circumstance of the bodies of the teeth yielding to pressure upon their base, shows that, even in the adult, they might be brought nearer to one another by art properly applied. (Hunter, John: Natural History of the Teeth, ed. 1, London, 1771, J. Johnson. In Weinberger, Bernard. W.: History of Orthodontia. Internat. J. Orthod. 2: 205, 1916.)
